1. Field of the Invention
The present invention relates to a mixed mode communication method and apparatus for communicating mixed mode document data including both character and image data.
2. Description of the Related Art
Document communication is conventionally performed through either a teletex device, which is a document communication apparatus for character data only or a facsimile device, which is a document communication apparatus for raster image data only. Mixed mode communication, in which mixed mode document data including both character and raster image data can be transmitted and received, was recommended by the International Consultative Committee for Telegraphy and Telephony (CCITT) in 1988 (CCITT recommendation T.501, T.522, T.561).
In general mixed mode document data, however, the amount of raster image data expressing figures in the document is larger than character data, even though the raster image data is typically compressed. Thus, it requires a long time to transmit or print the raster image data.
Generally, the raster image data in the mixed mode data is useful for supplementing an explanation given by characters. However, sometimes the meaning of the contents in the document can be understood even when the raster image data representing figures are deleted from the mixed mode document data. For example, a galley proof document may not need figures represented by the raster image data to be understood. In such a case, it may be unnecessary to transmit the raster image data, and only character data needs to be transmitted. In prior communication devices, however, it is impossible to separate the character data from the raster image data before transmitting the mixed mode document data.